1. Field of the Invention
This invention relates to pumpable, surfactant compositions of alkanolamine salts of alkyl phosphate esters. More particularly, this invention relates to readily pumpable, concentrated compositions of high solids content of alkanolamine salts of alkyl phosphate esters.
2. Description of Related Art
Surfactants and mixtures of surfactants are employed in a variety of industrial, commercial and domestic applications. Often, there is a need for a surfactant to be in a pumpable or fluid form for addition to formulations. Such a form is convenient and affords cost savings in handling and storage as well as ease and convenience in formulating products therewith. It is desirable for the surfactant to be available in such form in as high a concentration or proportion of surfactant or active ingredient as possible.
There are difficulties in using alkyl phosphate ester compositions of high solids content. Such compositions can be rigid or immovable, non-flowable or non-pumpable gels rather than easily handled fluid solutions. Further, phase separation can occur during production or subsequent storage of such compositions. In most instances, it has been impossible to effectively produce fluid or pumpable phosphate ester salt compositions above about 30 to 40% by weight active ingredient in water without the use of organic solvents or other co-surfactants or above about 60 wt % with their use.
To address these difficulties, various approaches have been attempted. U.S. Pat. Nos. 4,753,754 and 5,139,781 disclose the use of a mixture of different surfactants. Another approach has been to formulate aqueous solutions of such surfactants with generally large amounts of alcohols or other solvents, such as propylene glycol, dipropylene glycol or ethanol, which act as thinners and solubilizing agents thereby lowering the viscosity of the solution and inhibiting the formation of a non-flowable gel. However, for preparation of many formulations, it is not desirable to employ surfactant mixtures; in fact, their use can unnecessarily complicate the formulation process. In cosmetic or personal care product formulations, there may be a need to avoid the use of alcohol or other organic solvents. Alternately, a water-free composition may be desired.
Moreover, the use of cosurfactant compounds such as alkyl sulfates or sulfonate salts is problematic since they impart undesirable and irritating side effects as disclosed in WO 01/10991 and diminish desirable properties of the phosphate surfactants.
It would be desirable to have surfactant compositions of high concentrations of alkyl phosphate ester salts in a stable, pumpable liquid form. It would further be desirable to have surfactant compositions that do not require the presence of co-surfactants or large amounts of organic solvents or water, adulterating additives, or performance reducing residual components.
An object of this invention is to provide such stable, pumpable or flowable surfactant compositions of high solids content, e.g. about 60 wt % or more, that are pumpable at typical industrial use temperatures.
Alkyl phosphate ester alkanolamine salts useful in the compositions of the present invention include those of the monoalkyl salts of formula I and those of the dialkyl salts of formula II: 
R1 to R3 are, individually, C8-22 linear or branched alkyl, alkenyl, alkaryl or aralkyl hydrocarbon moieties, which optionally may contain carbocyclic rings. The subscripts a and b, individually, may be the same or different and are integers from 0 to 8 with the proviso that the sum of the a and b is less than or equal to 8. The subscripts n and m, individually, may be the same or different and are integers of from 2 to 4. Z1 and Z2 are, individually, hydrogen, alkali metal, ammonia or an alkanolamine according to formula III below with the proviso that at least one of Z1 and Z2 must be an alkanolamine according to formula III below. Z3 is an alkanolamine according to formula III below.
Alkanolamines useful in preparation of the alkyl phosphate ester salts of the present invention have the following formula III: 
R4 to R6 are, individually, hydrogen or C1-8, linear or branched alkyl, alkenyl, alkaryl or aralkyl hydrocarbon moieties, which optionally may contain carbocyclic rings. At least one of the three amine substituents is different from the other two. For at least one of the three substituents on the amine nitrogen, the sum of s and t (s+t) or v and w (v+w) or x and y (x+y) is equal to or greater than 1 and the corresponding R (R4, R5 or R6) is hydrogen. The subscripts p and q, individually, may be the same or different and are integers from 2 to 4. The subscripts s, t, v, w, x, and y, individually, may be the same or different and are integers of from 0 to 10, with the proviso that the sum of all six subscripts is less than or equal to 12.